I'll show you what's stupid
No, I will show you, here is the very same question you already asked 5 years ago:
http://www.elitetrader.com/et/index.php?threads/wanted-trading-laptop.214003/
Not to mention:
1. Unless you gave specifics (size, weight, battery life,etc), we can't answer your question.
2. Laptops are dirt cheap nowadays, you should buy a new one.
3. This is an instrument your livelihood is depending on and you wanna save a few bucks???